Your heraldic device (informally, your "coat of arms") is essentially your
personal "logo," and identifies you the way a company's logo identifies the
company. On a banner, it tells everyone you're at an event. On a shield, it
tells who's on the field fighting. On tableware, it tells whose place it's
at. On clothing, it tells who's in the clothing.

The heraldic device originated in war. During the chaos of battle, you had
to decide within seconds whether someone approaching was friend or enemy.
The device evolved to allow this; painted on a shield, it told who was
behind that shield. It was so helpful for identification during war that it
soon spread into peacetime use as well.

Since a device identified the man who displayed it, it was very important
that no two men have the same device. Colleges of Arms came into being to
resolve conflicting claims on a device, and the heralds gradually assumed
the job of keeping track of who owned which device. In the S.C.A., we have
our own College of Arms to insure that each member has his or her own
unique device.

A heraldic device is made of a number of charges (objects,
creatures, or geometric shapes) arranged on a field (or
background). Ideally, the result is simple, memorable, and easily
identified. To help you create a good device, the heralds restrict the
possible colors, poses, and arrangements of charges in your device.
they do not restrict the objects or creatures you can choose from
(except that you may only use period objects or creatures). Nor do
the heralds care what artistic style you draw your device in, as long as
the style was used in the heraldry of some place or time. You can, for
example, use the smooth cat-like lions of the 12th century, the wild-haired
lions of the 15th century, or the naturalistic lions of the late 16th
century.

Good devices have as few charges and colors as possible. The best devices
fill the roughly triangular shield with one or three identical charges, and
use only two colors (examples 1 and 2). More often, you'll have to use
more than one kind of charge, or more than two colors. Even then, you
should use as few kinds of charges (and as few of each kind) as you can,
and no more colors than you must.

Good devices repeat themselves. If the same kind of charge appears three
places, all three are identical. They're the same color, in the same pose,
and facing the same direction (examples 2-4). "Mirror imaging," with
charges that face one another, is a modern style; it wasn't used in
medieval heraldry.

Good devices make it easy to identify each charge. Animals are posed to
show as much of the animal as possible (examples 1 and 4). Other charges
are drawn to make them as distinctive as possible. And all charges are
drawn as large as possible while still fitting in the space available.

Finally, good devices have high contrast between their parts. As much as
possible, light charges (white, silver, yellow, or gold) are put on dark
fields (red, green, blue, purple, or black), and vice versa. (Traffic and
street signs all do this, to be as easy as possible to read.)

When you design your device, always work with your local or Kingdom
heralds. They're there to help you, and they're happy to do so. They know
the rules, and they know how to design good devices. As well, they can show
you various charges you can use. When you're ready, they can even make sure
your device is different from any other device in the S.C.A.

Get together with your herald and his books, or drop by a "Heraldic
Consultation Table" at any event which has one.

Once your device looks legal and unique, make sure you like it. Put it up
on your refrigerator, or in your office, for a few weeks. If you're still
as happy with it afterwards, give it to the heralds to begin the process of
"registering" it, so it can be uniquely yours in the S.C.A.

You can find more information here!
Our local Herald can also answer any questions or
help you submit your device for approval.